Intersection Control Evaluation (ICE)
Policy Directive 13-02 calls for the implementation of Intersection Control Evaluation (ICE) to projects concerning the following:
ICE is a two-step process that allows engineers to justify the installation of traffic signal systems, yield control (roundabouts), and multi-way stop control at state highway intersections and interchanges. It also helps identify effective intersection traffic control strategies and alternative treatments, approaches, and configurations for particular conditions as well as estimate the relative effectiveness and impacts of specific control strategies.
Step 1: Assessment of Control Alternatives
The objective of the first step in ICE is to identify access solution concepts that merit further consideration. To do this, we must understand the need, identify what strategies/configurations will meet the need, and assess to eliminate non-viable and impractical strategies.
For this project, stop, yield (roundabout), and signal control were considered for each intersection. The feasibility of these control types were evaluated for each intersection to determine if the control type should proceed to the next step or be eliminated. Since proposed intersections are new, other control types were not considered as implementing anything too exotic may be unnecessary and/or confuse drivers.
Step 2: Engineering Analysis of Control Alternatives
The objective of step two is to analyze and compare each control alternative to each other and determine the best option for the specific intersection. It is important that intersection cost and performance are considered in the analysis.
Data provided by Caltrans, Synchro 8, and SimTraffic 8 were used for this analysis. Parameters considered for each control type include total intersection delay, fuel use, and total stops. The total network was also analyzed to determine if the control affected the total network positively or negatively.
Weighted decision matrices were used here to determine which type of control should be used for each intersection. To create these matrices, many variables had to be created and determined using engineering judgment. These variables are:
Each of these variables are then assigned a weight. Then a score is given to each control type, and a total score is given afterwards. The control type with the highest overall score is the chosen control type.
Tight Diamond Control Summary
Split Diamond Control Summary
Partial Clover Control Summary
SPUI Control Summary
ICE documents are available for download as PDF files in the link below.